Purpose: Previous studies have shown a relationship between obstructive sleep apnea (OSA) and erythrocyte sedimentation rate (ESR), a representative marker for inflammation. We aimed to elucidate the possible association between elevated ESR and OSA severity.
Methods: A total of 341 patients who visited a sleep center were retrospectively enrolled. Subjects underwent physical examination, overnight polysomnography (PSG), and blood sampling for ESR and high-sensitivity C-reactive protein (hs-CRP). We compared the ESR and hs-CRP level to OSA severity and measured their correlation with other PSG parameters.
Results: The ESR was significantly higher in patients with severe OSA (apnea-hypopnea index (AHI) ≥ 30) than those with simple snoring (AHI < 5; P = 0.016), mild OSA (5 ≤ AHI < 15; P = 0.010), and moderate OSA (15 ≤ AHI < 30; P = 0.042). Similarly, the hs-CRP level in patients with severe OSA was significantly higher than that in patients with simple snoring (P = 0.006) and mild OSA (P = 0.013). Multivariate analysis also showed that elevated ESR was associated with moderate and severe OSA (adjusted OR = 2.231 (P = 0.048) and 2.606 (P = 0.002), respectively) after adjusting for sex, age, body mass index, smoking, hypertension, diabetes mellitus, and hyperlipidemia. However, elevated hs-CRP was not associated with the OSA severity.
Conclusions: ESR more closely correlated with PSG parameters recorded during sleep hypoxic episodes than hs-CRP. Moreover, the ESR may be useful to predict the OSA severity because moderate and severe OSA were independently associated with an elevated ESR.
Keywords: C-reactive protein; Erythrocyte sedimentation rate; Obstructive sleep apnea; Severity.